This gearing as part of an apparatus with one or more screws, in particular an extruder, has been described in DE-AS 1729149. There are provided in the known extruder gearings an intermediate gear arranged coaxially in the ring gear and a total of four pinions of equal size which mesh on one hand with the internal teeth of the ring gear and on the other hand with the external teeth of the intermediate gear. Two of the four pinions work as output pinions and the other two as driving pinions. The two driving pinions, which are spaced from each other somewhat more than the two output pinions, are approximately radially opposite to the output pinions, which serve to drive co-rotational double screws and accordingly are arranged close together.
The known gearing with four pinions requires a reduction gear for power division or torque division over the two driving pinions.
From DE-PS 2619019 is known an extruder gearing similar to the discussed above gearing, the intermediate gear of which meshes only with a driving pinion referred to as central pinion and with the internal teeth of the ring gear. The central pinion further is in engagement with an output pinion, which also meshes with the internal teeth of the ring gear. The center axes of all gears and pinions lie in a plane along the diameter of the ring gear.
The central pinion is disposed on a continuous input and output shaft and has the same diameter as the output pinion, while the diameter of the intermediate gear is double the diameter of the pinion and one-half the size of the ring gear diameter. As the central pinion and the output pinion mesh, only extruders with counter-rotating double screws can be driven by the known extruder gearing.